1. Field of the Invention
The present invention relates to a screw setting tool including a housing, a tool spindle located in the housing and axially displaceable relative thereto, a bit stop provided in the housing and adjustable in a direction parallel to a screw-in direction, the bit stop limiting an axial displacement of the tool spindle in a direction opposite to the screw-in direction, a spring for biasing the tool spindle in the screw-in direction, and a torque clutch for connecting the tool spindle with a drive motor and including a first clutch member driven by the drive motor and having a toothed outer profile cooperating with a corresponding toothed profile of a drive motor shaft, a second clutch member fixedly connectable with the tool spindle for joint rotation therewith, an intermediate clutch member located between the first and second clutch members and supported on the tool spindle for rotation there around and an axial displacement relative thereto, the first and intermediate clutch members having cooperating cams, and the intermediate and second clutch members having on their adjacent surfaces cooperating claws for forming a rotation-transmitting connection between the intermediate and second clutch members.
2. Description of the Prior Act
European Publication EP-A-O 195 853 discloses a screw setting tool including a bit stop and a quite and wear-free torque clutch. The bit stop is located in the tool housing and is adjustable in a direction parallel to the screw-in direction relative to the housing. The torque coupling has three clutch members, spaced first and second clutch members and an intermediate clutch member located there between. The first clutch member is formed as a toothed gear and is connected with an output shaft of the drive motor for joint rotation therewith. The second clutch member is connected with the tool spindle which receives, at its free, facing in the screw-in direction end, a driving tool. The intermediate clutch member, which is rotatably supported on the tool spindle, has a shape of a disc and serves for transmitting torque from the first clutch member to the second clutch member. The first clutch member and the intermediate clutch member have projecting cams which are form lockingly engaged in each other during the screw-in process. The cam flanks are inclined in the screw-in direction. Claws, which are constantly engaged in each other, are provided between the intermediate clutch member and the second clutch member. The claw flanks are partially inclined and toward their free end, extend parallel to the screw-in direction.
Before start of the screw-in process, the screw setting tool, which is disclosed in EP-AO-195,683 is pressed against a constructional component into which a screw has to be screwed-in. Upon the tool being pressed against the constructional component, all clutch members and a spring, which is arranged between the first and intermediate clutch members, are pressed toward each other. Upon actuation of the drive motor, the torque acting on the spindle increases, and the intermediate clutch member, together with the first clutch member, rotate, in the circumferential direction, relative to the second clutch member. During the relative rotation of the intermediate clutch member, together with the first clutch member, with respect to the second clutch member, the claws, which are provided between the intermediate and second clutch members, slide along their inclined, in the screw-in direction, flank sections until the sections, which extend parallel to the screw-in direction, abut each other.
Upon the screw being screwed-in, the tool spindle moves relative to the housing and to the bit stop in the screw-in direction. Upon the displacement of the tool spindle in the screw-in direction, the second clutch member and the intermediate clutch member move slowly away from the first clutch member. The contact area between the cams of the first and intermediate clutch members becomes smaller and smaller. When the screw reaches the desired depth, both cams become disengaged, and the first clutch member can freely rotate relative to the intermediate member. The preloaded spring presses the intermediate clutch member toward the second clutch member. Because of sliding of the claws of the intermediate and second clutch members along their inclined sections, the intermediate clutch member is rotated relative to the second clutch member in a direction opposite to the direction of rotation of the first clutch member. At that, the intermediate clutch member moves toward the second clutch member by an amount equal to the extension of the inclined sections of the claws in the direction parallel to the screw-in direction. At the end of the screw-in process, the cams of the first and intermediate clutch members are spaced from each other in the direction parallel to the screw-in direction.
A drawback of the screw setting tool disclosed in EP-AO 195 853 consists in that the claws, because of their specific shape, cannot be economically produced.
Accordingly, an object of the present is to provide a screw setting tool which can be economically produced.
Another object of the present invention is to provide a screw setting tool which would provide for a rapid and reliable screw-in of a screw.